Fuel cells provide electricity from chemical oxidation-reduction reactions and possess significant advantages over other forms of power generation in terms of cleanliness and efficiency. Typically, fuel cells employ hydrogen as the fuel and oxygen as the oxidizing agent. The power generation is proportional to the consumption rate of the reactants.
A significant disadvantage which inhibits the wider use of fuel cells is the lack of a widespread hydrogen infrastructure. Hydrogen has a relatively low volumetric energy density and is more difficult to store and transport than the hydrocarbon fuels currently used in most power generation systems. One way to overcome this difficulty is the use of reformers to convert the hydrocarbons to a hydrogen rich gas stream which can be used as a feed for fuel cells.
Hydrocarbon-based fuels, such as natural gas, LPG, gasoline, and diesel, require conversion processes to be used as fuel sources for most fuel cells. Current art uses multi-step processes combining an initial conversion process with several clean-up processes. The initial process is most often steam reforming (SR), autothermal reforming (ATR), catalytic partial oxidation (CPOX), or non-catalytic partial oxidation (POX). The clean-up processes are usually comprised of a combination of desulphurization, high temperature water-gas shift, low temperature water-gas shift, selective CO oxidation, or selective CO methanation. Alternative processes include hydrogen selective membrane reactors and filters.
The hydrogen-rich reformate produced in such conversion or reforming processed typically contain moderate to high levels of water in the form of steam. Although most types of fuel cells require a certain level of humidity to operate efficiently, the presence of excess water can flood the fuel cell and severely inhibit the electrochemical reaction. Furthermore, water removed from the hydrogen-gas reformate can contain unacceptable levels of combustible gases. Thus, water separated from a hydrogen-rich reformate stream cannot simply be routed to a domestic drain or sewage system.
In addition, there is a need to ensure the safe operation of a fuel processing systems so that the failure of any of the fuel processing subsystems does not result in an immediate release of combustible gases or other potentially hazardous materials to the local environment. Thus, there remains a need for a simple unit for converting a hydrocarbon-based fuel to a hydrogen-rich gas reformate for use in conjunction with a fuel cell, that is capable of removing and safely disposing of water separated from a hydrogen-rich reformate as well as other materials that may be present in an integrated fuel processing-fuel cell system.